AgustaWestland’s No. 2 AW609 broke up in midair during high-speed tests in late October, R&WI has learned, and international accident and crime investigators are combing through data from telemetry, flight recorders, systems designs and wreckage for clues as to why.
Among other areas, investigators are working to ensure they understand the design and function of the software laws for controlling movement of the AW609’s flight surfaces, nacelles and rotors.
Prototype No. 2 (bearing the registration N609AG) was 27 min into the flight test on Oct 30 when real-time telemetry was lost, according to AgustaWestland, which added that there was no further contact. The aircraft was flying in restricted military airspace during the flight tests. AgustaWestland said tests scheduled for that day included high-speed ones that “had already successfully been performed” by the No. 1 prototype.
Wreckage of the civil tiltrotor was found in the small town of Santhià, about 30 nm west-southwest of the aircraft’s departure point, AgustaWestland’s base at Cascina Costa di Samarate.
The dispersion of wreckage is a key indicator that the aircraft broke up in flight. Witnesses on the day of the crash reported an explosion and break-up in flight, but such reports are common after aircraft accidents.
Debris landed in cornfields less than a half-mile from Santhià. Major parts—but not all of the aircraft—landed within about 300 ft of each other in one field. These included the two engine nacelle/rotor sets, which were separate from each other and each of which appear to have wing sections attached. The fuselage landed nearby, with the empennage attached but with sections of the horizontal stabilizer missing.
Each of these wreckage sets was on fire when people nearby arrived at the scene, but there is no evidence of fire damage to wide areas of the cornstalk stumps surrounding the debris. Ground around the debris was not disturbed significantly, according to one scene witness.
A local prosecutor immediately launched a criminal investigation and asserted control over the crash site and wreckage. In parallel, Italy’s National Agency for the Safety of Flight (whose Italian acronym is ANSV) is conducting an accident investigation with participation from the U.S. FAA and NTSB, Italy’s civil aviation authority (ENAC) and the European Aviation Safety Agency (EASA). AgustaWestland said it is cooperating with the investigations.
Accident investigators are examining telemetry from the aircraft as well as its cockpit voice and flight data recordings and evidence in the wreckage.
Italian investigators have enlisted Bell Helicopter to assist in their examination of the tiltrotor’s flight control laws. The 609 early on (in the late 1990s) was a Bell-Agusta effort, but AgustaWestland took full ownership of the program in 2011. However, Bell engineers developed the flight control laws for the aircraft.
Accident investigators are scouring flight data, wreckage and control laws for clues to the AW609 prototype’s midair breakup. Photo courtesy of AgustaWestland